I just found out how to directly show the high quality version on the movie page. It`s a tremendous increase in quality for some videos.
Most of the artifacts are gone. Text is displaying nicely and the playback is in stereo!
Some artists, as a reaction to my yesterday`s news seemed to have removed their videos from YouTube. Please upload them again in higher quality and let me know.
Also I have removed some videos that despite the higher quality weren`t displaying nicely.

You can find a lot of information on YouTube on how to obtain a high qualityYouTube video. Just do a video tutorial search.

I suggest that you revisit the video page and have a look at the increased quality.